Container end closure attachment

ABSTRACT

An improved means for attaching a metal end closure to a container body having an upstanding straight marginal edge portion wherein the end closure is provided with a peripheral channel defined by inner and outer depending straight wall portions, the inner depending straight wall portion merging with the central panel of the end closure, and said channel including said inner and outer depending straight wall portions being bonded to the upstanding straight marginal edge portion of said container body by means of a suitable thermoplastic adhesive.

United @tates Patent [191 Godar CONTAINER END CLOSURE ATTACHMENT [75]Inventor: Joseph L. Godar, Wauconda, Ill.

[73] Assignee: American Can Company,

Greenwich, Conn.

22 Filed: Jan. 3, 1973 21 Appl. No.: 320,695

[52] US. Cl. 229/55; 156/69; 156/331; 156/334; 220/67; 260/857 UN;260/876 B;

[51] Int. CI. B65D 3/10; B65D 7/42 [58] Field of Search 229/55, 5.6;220/66, 67, 220/81 R; l61/102,105,106,107,125, 139,

B, 876 B, 857 UN, 18 N, 24; 156/334, 69;

117/132 BE, 132 C, 155 R, 155 UA, 75

[56] References Cited UNITED STATES PATENTS 2,467,182 4/1949 Beattie229/5.5 X 3,251,708 5/1966 Schmetterer. 1 17/132 BE X 3,303,954 2/1967Beaudet 161/186 X 3,322,318 5/1967 Felton et al 229/56 X 3,406,891l0/l968 Buchner et a1.

3,427,269 2/1969 Davis et a1. 3,430,805 3/1969 Buchner et al. 220/663,448,178 6/1969 Flanagan 260/897 B 3,497,466 2/1970 Markulin et al. 117/75 X 3,615,106 10/1971 Flanagan et al 260/897 B X 3,630,980 12/1971Russell 260/93.3 X 3,635,861 l/1972 Russell 260/93.3 X 3,645,822 2/1972Widiger et a1 161/256 X 3,703,434 11/1972 Schaff 161/186 X 3,722,7322/1973 Edlund 229/55 X 3,736,281 5/1973 Russell 260/876 B X OTHERPUBLICATIONS Cagle, Charles V., Handbook of Adhesive Bonding, pp. 81 to8-5 relied on.

Primary Examiner-George F. Lesmes Assistant ExaminerAlan T. McDonaldAttorney, Agent, or FirmRobert P. Auber; Ernestine C. Bartlett; JosephJ. Orlando ABSIRACT An improved means for attaching a metal end closureto a container body having an upstanding straight marginal edge portionwherein the end closure is provided with a peripheral channel defined byinner and outer depending straight wall portions, the inner dependingstraight wall portion merging with the central panel of the end closure,and said channel including said inner and outer depending straight wallportions being bonded to the upstanding straight marginal edge portionof said container body by means of a suitable thermoplastic adhesive.

5 Claims, 2 Drawing Figures US. Patent Oct. 14, 1975 (3 wwwwwwmmwi i iii i i Iii! xvv dv/il fl AV v CONTAINER END CLOSURE ATTACHMENT Thepresent invention relates generally to a means for attaching metallicend closures to container bodies. More particularly, the presentinvention relates to an improved means for attaching metallic endclosures to container bodies having upstanding straight marginal edgeportions wherein the structure of the end closure in cooperation withsuitable bonding agents produces a container adapted for containingliquids under pressure.

There are at the present time several different methods of attachingmetal end closures to container bodies, whether the container body beformed of metal, of a composite material, or of plastic. Usually suchend closures are attached to the container body by means of some form ofmechanical engagement between the end closure and the marginal edgeportion of the container body. In fact, without some form of mechanicalengagement of the end closure to the container body it has generallybeen impossible to contain a pressurized product within a container.Furthermore, it has been found necessary to use sealing compounds in theend seams for the purpose of hermetically sealing the containers andpreventing leakage of the contents therefrom.

Over the years many attempts have been made to improve end seamingtechniques primarily for the purpose of economy and secondarily toimprove the aesthetic appearance of the containers thereby making thecontainers more appealing to the consuming public. Exampples of suchattempted improvements are illustrated by U.S. Pat. No. 2,467,182, toBeattie, granted Apr. 12, 1949, U.S. Pat. No. 2,303,322, to Bigger,

granted Dec. 1, 1942, and U.S. Pat. No. 2,801,648, to Anderson et al.,granted Aug. 5, 1957. The Beattie patent discloses an end attachmentmeans wherein the metallic end closure comprises a peripheral channeldefined by inner and outer depending straight wall portions, the innerdepending straight wall portion merging at its lowest edge with thecentral panel of the end closure. Sealing compound covers the interiorof the channel which is positioned about the upstanding straightmarginal edge portion of the container body and the depending straightwalls defining the channel are crimped to mechanically engage theupstanding edge portion of the container body. The Bigger patentdiscloses a somewhat similar end seam construction wherein themechanical engagement of the marginal edge portion of the side wall ofthe container body by the metallic end closure is accomplished byproviding a hemmed curl in the outer depending straight wall of thechannel portion which is pressed into the side wall of the containerbody at the marginal edge thereof in order to lock the end closurethereon. The sealing compound or adhesive is applied in the Biggerpatent along the inside of the inner depending straight wall portion andthe bottom of the channel portion in order to aid in securing the endclosure onto the container body. It is to be noted that in both theBeattie and Bigger patents it is mechanical means that is primarily usedto secure the end closure onto the container body while the sealingcompound or adhesive is used in the end seam for the secondary purposeof hermetically sealing the container used, to a much less extent, insecuring the end closure onto the container body. With respect to theAnderson et al. patent, a lap seam is shown which is formed solely bymeans ofa bonding agent which securely bonds the depending skirt or wallportion of a metallic end closure to the upstanding straight marginaledge portion of the side wall of the metal container body. It is to bepointed out that a major disadvantage of this construction is that theraw metal edge at the marginal edge portion of the side wall of thecontainer body, which is usually susceptible to attack, is exposed tothe contents of the container since the bonding agent is applied only tothe outer surface of the marginal edge portion of the side wall of thecontainer body. In addition, with respect to the Anderson et al.construction, the bonding agent employed with this end seaming techniquemust necessarily be very strong and therefore expensive because of thelimited area over which the bonding agent is used. Still, the Andersonet al. patent does not disclose that such a construction will contain apressurized product.

Yet another purpose of improved end seaming techniques is to minimizethe effect of the end seam thickness. Relatively thick end seams,usually termed chimes, result in container abuse problems as well aspackaging difficulties. Thus, a recent innovation in this area is thenecked-in metal container wherein the marginal edge portion of thecontainer body is necked-in thereby resulting in an end seam which doesnot extend beyond the diameter of the container. However, the productionof necked-in containers is relatively expensive, requiring a higherworking of the metal in the side wall of the container, and,furthermore, as the body wall thickness is made smaller and lessresistant to vertical pressures, the necked-in configuration provides aready site for beginning the collapse of the body wall when subjected tovertical pressures.

It is, therefore, a primary object of the present invention to providean improved means for attaching a metalllic end closure to a containerbody which eliminates any mechanical attaching means and is economical,simple in design, and as effective as prior art end closure attachingmeans and also minimizes the effect of end seam chimes.

The above object, as well as others which will hereinafter becomeapparent, is accomplished according to the present invention byproviding improved means for the attachment of metallic end closures tocontainer bodies, whether of metallic, composite, or plasticconstruction, wherein the end closure is provided with a peripheralchannel defined by inner and outer depending straight wall portions, theinner depending straight wall portion merging with the central panel ofthe end closure, and said channel including said inner and outerdepending straight wall portions being bonded to the straight marginaledge portion of said container body by means of a thermoplasticadhesive.

The present invention will be described and understood more readily whenconsidered together with the embodiment shown in the accompanyingdrawing, in which:

FIG. 1 is a perspective view of a container having an end closureattached thereto in accordance with the present invention; and

FIG. 2 is an enlarged partial cross-sectional view of the container ofFIG. 1 taken along line 22 of FIG. 1.

Referring now to the drawing, there is shown in FIG. 1 a container,generally designated 10, which, although shown to be a fiber orcomposite type container, may

also be a thin walled container constructed of metal, plastic, etc.Container is comprised of a container body, generally designated 12,which, if constructed of a fibrous material, is formed by helicallywinding a sheet of composite material into the cylindrical shape shownhaving a spiral seam, generally designated 14. The open ends ofcontainer body 12 are covered by a pair of metallic end closures,generally designated 16 and 18, which are joined to container body 12 atend seams 20 and 22, respectively.

As clearly seen in FIGS. 1 and 2, end closure 16, which may beconstructed identically with end closure 18, is formed having agenerally planar central panel, designated 24, surrounded by aperipheral reinforcing groove, generally designated 26. Reinforcinggroove 26 merges at its outer edge, designated 28, into an upwardlydepending substantially straight inner wall portion, generallydesignated 30, the upper end of which merges with an outwardly extendingflange, designated 32. Flange 32 merges with a downwardly dependingsubstantially straight outer wall portion 34, which is formed parallelwith depending inner wall portion 30. Inner and outer depending straightwall portions and 34 define a channel, generally designated 36, whichperipherally surrounds the end closure.

End seam 20, which joins end closure 16 to contaianer body 12, and whichmay be identical to end seam 22 which joins end closure 18 to containerbody 12, is formed by the girdling of the upstanding straight marginaledge portion, generally designated 38, of the open end of container body12 by channel 36 defined by the inner and outer depending straight wallportions 30 and 34. As can readily be seen in FIG. 2, the thickness ofchime of the end seam 20 is relatively small, amounting to only threethicknesses of material and only a single thickness of material beyondthe side wall of container body 12.

The main feature of the invention is the provision of an adhesive,generally designated 40, in channel 36 which adhesively bonds endclosure 16 to container 12. As seen in FIG. 2, the adhesive 40, whichbonds the surface 42 of depending straight inner wall portion 30 facingchannel 36 to the inner surface 44 of the upstanding straight marginalportion of container body 12, is subjected to shear stress produced bythe internal forces within the-container rather than peel stress. It isto be appreciated in this context that the peel strength of mostadhesives is very weak in comparison to the shear strength of theadhesives, thus, the present construction takes full advantage of thismaterial property of adhesives. This form of construction, wherein theinner depending straight wall portion 30 is substantially straightthereby decreasing the peel stress to which adhesive is subjected,increases the buckle resistance of the end closuure at the reinforcinggroove 26. In addition, adhesive 40 bonds surface 46, which faceschannel 36, of downwardly depending outer wall 34 to outer surface 48 ofupstanding straight marginal edge portion 38 of container body 12. Thus,the surface area of container body 12 bonded to end closure 16 isrelatively large, being the inner and outer surfaces 44 and 48 ofmarginal edge portin 38.

It is to be noted that the surfaces of the end closure and containerbody which are bonded together are protectively coated, by coatingmaterials 50 and 52 respectively, in order to insulate the materialsfrom which the container is formed from the contained product, which,

in the usual case, is corrosive. It is therefore necessary that theadhesive chosen to attach end closure 16 to container body 12 becoordinated with the coating materials applied to the surfaces of theend closure and the container body. Thus, heat activated adhesives,based on an ethylene-acetate terpolymer, a butadienestyrene-blockcopolymer, and a polyamide polymer have successfully been utilized inattaching coated end closures to coated fiber or metallic containerbodies. The protective coatings 50 and 52 which are utilized with theabove identified .thermoplastic adhesives are, with respect to ametallic end closure, a modified epoxy type coating and, with respect toa metallic container body, a vinyl type coating over a modified epoxytype base coating, and with respect to a composite body, a modifiedepoxy type coating together with slip compound, all of which arecommonly used in the industry for the purposes of protectingthecontainer materials from corrosion, etc. The slip compound utilizedin the coating for the composite container body is specifically for thepurpose of lubrication between the container body being formed and themandrel with which the body is formed.

The ethylene-vinyl-acetate acid terpolymer based adhesive is produced bymixing 65 parts by weight of an ethylene-vinyl-acetate organic acidterpolymer with 35 parts by weight of a polyterpene resin, this is thendissolved in 200 parts by weight of a heated solvent, such as anaromatic petroleum hydrocarbon. When the solution cools it becomes ahard gel which may be stored until use. When the adhesive is to beapplied it is reheated to about 150 F., the channel 36 of end closure 16or the straight marginal edge portion 38 is lined with the adhesive andthen heated at 200 F. to drive off the solvent. The adhesive lined endsor container bodies may then be stored until ready for attachment atwhich time the adhesive is reactivated by heating to 300 F. Thereactivated adhesive is then ready to adhesively bond the end closuresto the container bodies. The ethylene-vinyl-acetate organic acidterpolymer preferably has a 20 percent by volume vinyl acetate contentwith an acid number of six. An example of a preferredethylenevinyl-acetate organic acid terpolymer is manufactured by E. I.DUPONT DE NEMOURS and Company and designated EP-3656-9.

The butadiene-styrene-block copolymer based adhesive is produced bymixing 56.71 parts by weight of a styrene-butadiene-block copolymer,having 25 percent by volume of the styrene molecule and percent byvolume of the butadiene molecule, with 21.22 parts by weight of apolyterpene resin, 21.22 parts by weight of a commarone-indene resin,and 0.85 parts by weight of an anti-oxidant. This is dissolved in 200parts by weight of a heated solvent, such as an aromatic petroleumhydrocarbon. When the solution cools it thickens slightly and can beapplied without the necessity of reheating. Like theethylene-vinyl-acetate acid terpolymer based adhesive it can be storeduntil ready for use and the application and results are also similar.Examples of a commercially available styrene-butadiene-block copolymersuitable for such use are Kraton l 101 and l 102 as produced by theShell Chemical Company.

The polyamide copolymer based adhesive is pro-' duced by mixing 75 partsby weight of a polyamide, having a meltindex range of 6 to 15 at 401 F.and which also must be soluble and remain a liquid solution at roomtemperature, with 25 parts by weight ofa polyterpene resin. This is thendissolved in heated solvents comprising 200 parts by weight of anaromatic petroleum hydrocarbon, 60 parts by weight of an acetone freediacetone alcohol and 60 parts by weight of an isopropyl alcohol. Thesolvents are heated to about 150 F. in order to effect a good solutionof the ingredients. The adhesive remains a homogenous liquid mixturewhen cooled to room temperature and can be applied anytime as such andheated to drive off the solvents. The adhesive can then be reactivatedand the ends applied to the container bodies by heating the adhesive toabout 400 F. Examples of commercially available polyamides suitable forsuch use are Milvex 1000 and Milvex 4000 produced by General Mills Inc.

It is to be noted that adhesive 40, as clearly seen in FIG. 2, fullyprotects the raw edge, generally designated 54, of the marginal edgeportion 38 of container body 12. Thus, it is impossible for the contentsof container to contact edge 54 which would corrode in the case of ametallic container body 12 or deteriorate in the case of a compositecontainer body 12 due to wicking.

It is understood that the foregoing general and detailed descriptionsare merely explanatory of the present invention and are not to beinterpreted as restrictive of the scope of the following claims.

What is claimed is:

l. A container, suitable for containing liquids under pressure,comprising:

a body portion having an upstanding marginal edge portion and a metallicend closure seamed to and covering at least one open end of said bodyportion, at least the portions of the surfaces within the seam having anepoxy-resin or vinyl-resin coating or combinations thereof appliedthereto;

said end seam being derived in the absence of mechanical locking of theend closure to the body portion and comprising (a) a channel surroundingthe periphery of the central panel of said end closure and defined byinner and outer depending straight wall portions wherein the innerdepending straight wall porption merges into the central panel of saidend closure and the outer depending straight wall portion is parallel tothe inner wall portion and merges with an outwardly extending flange andb) a thermoplastic adhesive bonding the inner surfaces of the channel tothe inner and outer surface of the upstanding marginal edge portion ofthe body; said thermoplastic adhesive being selected from those derivedfrom the group of:

l. a mixture consisting essentially of about 65 parts by weight of anethylene-vinyl acetate-organic acid terpolymer having a 20 percent byvolume vinylacetate content and an acid number of 6 and about 35 partsby weight of a polyterpene resin;

2. a mixture consisting essentially of about 56 parts by weight of astyrenebutadiene block copolymer having about 25 percent by volumestyrene and about percent by volume butadiene, about 21 parts by weightof a polyterpene resin and about 21 parts by weight of a coumaroneindeneresin; and

3. a mixture consisting essentially of about 75 parts by weight of apolyamide having a melt index range of from about 6 to about 15 at 401Fand about 25 parts by weight of a polyterpene resin.

2. The container as defined in claim 1 wherein said thermoplasticadhesive is derived from a mixture consisting essentially of about65parts by weight of an ethylene-vinyl acetate-organic acid terpolymerhaving a 20 percent by volume vinylacetate content and an acid number of6 and about 65 parts by weight of a polyterpene resin.

3. The container as defined in claim 1 wherein said thermoplasticadhesive is derived from a mixture consisting essentially of about 56parts by weight of a styrenebutadiene block copolymer having about 25percent by volume styrene and about 75 percent by volume butadiene,about 21 parts by weight of a polyterpene resin and about 21 parts byweight of a coumaroneindene resin. 4. The container as defined in claim1 wherein said thermoplastic adhesive is derived from a mixtureconsisting essentially of about 75 parts by weight of a polyamide havinga melt index range of from about 6 to about 15 at 401F and about 25parts by weight of a polyterpene resin.

5. The container as defined in claim 1 wherein said body portioncomprises fibrous material.

1. A MIXTURE CONSISTING ESSENTIALLY OF ABOUT 65 PARTS BY WEIGHT OF ANETHYLENE-VINYL ACETATE-ORGANIC ACID TER-
 1. A CONTAINER, SUITABLE FORCONTAINING LIQUIDS UNDER PRESSURE, COMPRISING: A BODY PORTION HAVING ANUPSTANDING MARGINAL EDGE PORTION AND A METALLIC END CLOSURE SEAMED TOAND COVERING AT LEAST ONE OPEN END OF SAID BODY PORTION, AAT LEAST THEPORTIONS OF THE SURFACES WITHIN THE SEAM HAVING AN EPOXY-RESIN ORVINYL-RESIN COATING OF COMBINATIONS THEREOF APPLIED THERETO, SAID ENDSEAM BEING DRIVED IN THE ABSENCE OF MECHANICAL LOCKING OF THE ENDCLOSURE TO THE BODY PORTION AND COMPRISING (A) A CHANNEL SURROUNDING THEPERIPHERY OF THE CENTRAL PANEL OF SAID END CLOSURE AND DEFINED BY INNERAND OUTER DEPENDING STRAIGHT WALL PORTIONS WHEREIN THE INNER DEPENDINGSTRAIGHT WALL PORPTIONS MERGES INTO THE CENTRAL PANEL OF SAID ENDCLOSURE AND THE OUTER DEPENDING STRAIGHT WALL PORTION IS PARALLEL TO THEINNER WALL PORTION AND MERGES WITH AN OUTWARDLY EXTENDING FLANGE AND B)A THERMOPLASTIC ADHESIVE BONDING THE INNER SURFACES OF THE CHANNEL TOTHE INNER AND OUTER SURFACE OF THE UPSTANDING MARGINAL EDGE PORTION OFTHE BODY, SAID THERMOPLASTIC ADHESIVE BEING SELECTED FROM THOSE DERIVEDFROM THE GROUP OF:
 2. a mixture consisting essentially of about 56 partsby weight of a styrenebutadiene block copolymer having about 25 percentby volume styrene and about 75 percent by volume butadiene, about 21parts by weight of a polyterpene resin and about 21 parts by weight of acoumaroneindene resin; and
 2. A MIXTURE CONSISTING ESSENTIALLY OF ABOUT56 PARTS BY WEIGHT OF A STYRENEBUTADIENE BLOCK COPLYMER HAVING ABOUT 25PERCENT BY VOLUME STYRENE AND ABOUT 75 PERCENT BY VOLUME BUTABIENE,ABOUT 21 PARTS BY WEIGHT PF A POLYTERPENE RESIN AND ABOUT 21 PARTS BYWEIGHT OF A COUMARONEINDENE RESIN, AND
 2. The container as defined inclaim 1 wherein said thermoplastic adhesive is derived from a mixtureconsisting essentially of about65 parts by weight of an ethylene-vinylacetate-organic acid terpolymer having a 20 percent by volumevinylacetate content and an acid number of 6 and about 65 parts byweight of a polyterpene resin.
 3. The container as defined in claim 1wherein said thermoplastic adhesive is derived from a mixture consistingessentially of about 56 PARTS by weight of a styrenebutadiene blockcopolymer having about 25 percent by volume styrene and about 75 percentby volume butadiene, about 21 parts by weight of a polyterpene resin andabout 21 parts by weight of a coumaroneindene resin.
 3. A MIXTURECONSISTING ESSENTIALLY OF ABOUT 75 PARTS BY WEIGHT OF A POLYMIDE HAVINGA MELT INDEX RANGE OF FROM ABOUT 6 TO ABOUT 15 AT 401*F AND ABOUT 25PARTS BY WEIGHT OF A POLTERPENE RESIN.
 3. a mixture consistingessentially of about 75 parts by weight of a polyamide having a meltindex range of from about 6 to about 15 at 401*F and about 25 parts byweight of a polyterpene resin.
 4. The container as defined in claim 1wherein said thermoplastic adhesive is derived from a mixture consistingessentially of about 75 parts by weight of a polyamide having a meltindex range of from about 6 to about 15 at 401*F and about 25 parts byweight of a polyterpene resin.
 5. The container as defined in claim 1wherein said body portion comprises fibrous material.